Prioritising items

[James_Dartnall]

Hello,

I have a question about prioritising. Say I have a processing plant with 20 processors in it and I have 3 types of item to be processed in the plant. I also have a queue of these items waiting to go into the plant, a rate at which these items join the queue and a rate at which the items exit the plant after being processed.

The question I have is how do I define the rate at which the items move from the queue into the plant such that no more than the number of processors available in the plant are sent in AND there is a prority list on the the item types - so that I always send in as many of item type 1 before I send in any of item type 2 and as many of item type 2 before I send in any of item type 3.

This example probably lends itself more to discrete event simulation than systems dynamics but I must use Vensim to solve it somehow, so any suggestions would be welcome. I can send an example vensim model of the problem, as I have it so far, if this will help clarify what I am asking.

I am using vensim vesion 5.3.

I have tried many ways of solving this problem with no luck so far so i would be very appreciative if anyone has a solution. Thanks in advance,
James

[bob@vensim.com]

It sounds like ALLOCATE BY PRIORITY will solve this problem directly - 20 is capacity and, priority s 10-item type and width should be set t0 0.25. If you have not already subscripted things by item type you will need to do so to get this to work.